The University of Texas Perry-Castañeda Map Library contains the most complete online archive of international topographic maps. If an area or country you need is not included, you should contact the Map Library directly to see if they have a map and just haven't scanned it yet. They may be able to do that for you if needed.
Another suggestion would be to browse the government websites of the countries you need and see if there is an equivalent of the US Geological Survey for that country.
Lastly, search in the library catalog, libraries.usc.edu and search for "topographic maps" + name of country to search for online and print maps in the collection.